93 RX7 won’t start
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Joined: Apr 2018
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From: germany
93 RX7 won’t start
So, I have an R1 FD rx7 RHD. I’m going to start by listing engine mods so you guys can get an accurate description of my car before diagnosing.
- Engine rebuilt 1000ish km ago
- stock twin turbos
- streetport
- simplified vacuum lines
- hks intakes
- side mount coil packs(brand new)
- OEM fuel system(brand new primaries)
- Apex’i PFC ECU(running base map)
- No catalytic converter, hks downpipe, mazdaspeed muffler
So starting at the beginning, after the rebuild the car didn’t start right away because one of my CAS was bad. After replacing it the car started up right away, a couple days and breaking the new rebuild in by letting it idle and the car randomly dies while idling. After trying and trying to get it started it will not start it stutters I’m cranking like something is preventing it from starting. After multiple diagnosis we cannot figure it out. I try replacing one of my primary injector connectors and cleaning the ECU grounds under the UIM. Car starts up and seems fine, although has trouble starting will start. I drive it all summer without any real issues, It doesn’t like to hot start though(yes I checked compression it is good). I put it away for winter and start it up this spring everything seems good. Driving for maybe 2 weeks and then one Sunday it dies while idling, try to start it back up and the same “Stuttering” while cranking is happening. I tried deflooding many times, and replaced the primary injectors. Cleaned the plugs every deflood. It is getting fuel, and it is getting spark. I re did the vacuum lines about a week ago so I know no vacuum leaks are present. One time it started roughly and it idled beautiful and then at about 57 degrees Celsius it died again before we could get to the throttle. I have added grounds, replaced sensors, checked spark, fuel, jumped the car, I’ve tried everything I can think of but something is stopping it from starting. I’m inclined to think it is something electrical but don’t even know where to start. Please any suggestions or opinions are welcome, I have 10 months to get the car up and running well so I can ship it back home to the states from Germany where I’m stationed currently
- Engine rebuilt 1000ish km ago
- stock twin turbos
- streetport
- simplified vacuum lines
- hks intakes
- side mount coil packs(brand new)
- OEM fuel system(brand new primaries)
- Apex’i PFC ECU(running base map)
- No catalytic converter, hks downpipe, mazdaspeed muffler
So starting at the beginning, after the rebuild the car didn’t start right away because one of my CAS was bad. After replacing it the car started up right away, a couple days and breaking the new rebuild in by letting it idle and the car randomly dies while idling. After trying and trying to get it started it will not start it stutters I’m cranking like something is preventing it from starting. After multiple diagnosis we cannot figure it out. I try replacing one of my primary injector connectors and cleaning the ECU grounds under the UIM. Car starts up and seems fine, although has trouble starting will start. I drive it all summer without any real issues, It doesn’t like to hot start though(yes I checked compression it is good). I put it away for winter and start it up this spring everything seems good. Driving for maybe 2 weeks and then one Sunday it dies while idling, try to start it back up and the same “Stuttering” while cranking is happening. I tried deflooding many times, and replaced the primary injectors. Cleaned the plugs every deflood. It is getting fuel, and it is getting spark. I re did the vacuum lines about a week ago so I know no vacuum leaks are present. One time it started roughly and it idled beautiful and then at about 57 degrees Celsius it died again before we could get to the throttle. I have added grounds, replaced sensors, checked spark, fuel, jumped the car, I’ve tried everything I can think of but something is stopping it from starting. I’m inclined to think it is something electrical but don’t even know where to start. Please any suggestions or opinions are welcome, I have 10 months to get the car up and running well so I can ship it back home to the states from Germany where I’m stationed currently
Welcome to the board. 
Well, I tend to agree with your assessment - that it's probably an electrical thing. In particular, you mentioned having to change one of the crank sensors before. Maybe you need to start fishing around the engine harness in that area. I'm not an FD guy, so get your grain of salt, but you have nothing to lose by looking into it.
Well, I tend to agree with your assessment - that it's probably an electrical thing. In particular, you mentioned having to change one of the crank sensors before. Maybe you need to start fishing around the engine harness in that area. I'm not an FD guy, so get your grain of salt, but you have nothing to lose by looking into it.
Joined: Nov 2011
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From: okinawa to tampa
Sounds a lot like a fuel issue to me. Check your fuel pressure. Actually check your fuel pressure. See that it HOLDS 43psi when you prime the pump. Also check that the pump itself is good and replace the oring at the stand pipe for the fuel pump.
Thread Starter
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Joined: Apr 2018
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From: germany
Also would not enough fuel pressure cause the car not to start? Or have a hard time starting?
Joined: Nov 2011
Posts: 3,425
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From: okinawa to tampa
Low fuel pressure will cause exactly that, yes. The problem becomes worse when the car is warmed up, if it starts at all.
You can put an aftermarket fpr with stock rails so long as you remove the stock one and attach the necessary fittings to the rail...... although there's no point to that. There are inline fuel pressure gauges that are used for diagnostics. If you don't have access to one then you can just replace the oring at the stand pipe and see if that helps and we can go from there.
it's just troubleshooting without the proper tools to confirm suspicions is extremely difficult since you would just be blindly replacing parts until the issue went away.
another way to check fuel pressure is watching injector duty cycle. An abnormally high duty cycle compared to the load is giveaway and also hitting 100% with relative ease is an indication. If you have a commander with your pfc then you can check it through there.
You can put an aftermarket fpr with stock rails so long as you remove the stock one and attach the necessary fittings to the rail...... although there's no point to that. There are inline fuel pressure gauges that are used for diagnostics. If you don't have access to one then you can just replace the oring at the stand pipe and see if that helps and we can go from there.
it's just troubleshooting without the proper tools to confirm suspicions is extremely difficult since you would just be blindly replacing parts until the issue went away.
another way to check fuel pressure is watching injector duty cycle. An abnormally high duty cycle compared to the load is giveaway and also hitting 100% with relative ease is an indication. If you have a commander with your pfc then you can check it through there.
Thread Starter
Junior Member
Joined: Apr 2018
Posts: 13
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From: germany
Low fuel pressure will cause exactly that, yes. The problem becomes worse when the car is warmed up, if it starts at all.
You can put an aftermarket fpr with stock rails so long as you remove the stock one and attach the necessary fittings to the rail...... although there's no point to that. There are inline fuel pressure gauges that are used for diagnostics. If you don't have access to one then you can just replace the oring at the stand pipe and see if that helps and we can go from there.
it's just troubleshooting without the proper tools to confirm suspicions is extremely difficult since you would just be blindly replacing parts until the issue went away.
another way to check fuel pressure is watching injector duty cycle. An abnormally high duty cycle compared to the load is giveaway and also hitting 100% with relative ease is an indication. If you have a commander with your pfc then you can check it through there.
You can put an aftermarket fpr with stock rails so long as you remove the stock one and attach the necessary fittings to the rail...... although there's no point to that. There are inline fuel pressure gauges that are used for diagnostics. If you don't have access to one then you can just replace the oring at the stand pipe and see if that helps and we can go from there.
it's just troubleshooting without the proper tools to confirm suspicions is extremely difficult since you would just be blindly replacing parts until the issue went away.
another way to check fuel pressure is watching injector duty cycle. An abnormally high duty cycle compared to the load is giveaway and also hitting 100% with relative ease is an indication. If you have a commander with your pfc then you can check it through there.
Joined: Nov 2011
Posts: 3,425
Likes: 489
From: okinawa to tampa
When you pull the fuel pump hanger from the gas tank, at the top of the of the fuel pump there will be a hat shape object. Under it will be the top of the fuel pump, an o-ring and some other peice that is split in half. Replace the o-ring. The pipe that goes from the top of the fuel pump to the hanger is the stand pipe......... or so as I'm referring to it anyway.
you can get the o-ring from mazda or you can get the Dorman fuel injector o-ring variety pack from auto zone or something..... I've used both options.
you can get the o-ring from mazda or you can get the Dorman fuel injector o-ring variety pack from auto zone or something..... I've used both options.
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Thread Starter
Junior Member
Joined: Apr 2018
Posts: 13
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From: germany
When you pull the fuel pump hanger from the gas tank, at the top of the of the fuel pump there will be a hat shape object. Under it will be the top of the fuel pump, an o-ring and some other peice that is split in half. Replace the o-ring. The pipe that goes from the top of the fuel pump to the hanger is the stand pipe......... or so as I'm referring to it anyway.
you can get the o-ring from mazda or you can get the Dorman fuel injector o-ring variety pack from auto zone or something..... I've used both options.
you can get the o-ring from mazda or you can get the Dorman fuel injector o-ring variety pack from auto zone or something..... I've used both options.
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From: Ny
Sounds to be a fuel related issue. I’d start with running a FPR to see where you are sitting. You can also check your plugs and see if they are dry or wet. This will kind of tell you if you have to much fuel being dumped or not enough.
Thread Starter
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Joined: Apr 2018
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From: germany
ive been checking the plugs they have fuel on them and it doesn’t seem to be too much, but I wasn’t sure so I was deflooding the car like 10 times and trying to start it but every time it did the same thing
Thread Starter
Junior Member
Joined: Apr 2018
Posts: 13
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From: germany
When you pull the fuel pump hanger from the gas tank, at the top of the of the fuel pump there will be a hat shape object. Under it will be the top of the fuel pump, an o-ring and some other peice that is split in half. Replace the o-ring. The pipe that goes from the top of the fuel pump to the hanger is the stand pipe......... or so as I'm referring to it anyway.
you can get the o-ring from mazda or you can get the Dorman fuel injector o-ring variety pack from auto zone or something..... I've used both options.
you can get the o-ring from mazda or you can get the Dorman fuel injector o-ring variety pack from auto zone or something..... I've used both options.
Last edited by Ludy Bahneman; Mar 18, 2019 at 11:05 AM.
Thread Starter
Junior Member
Joined: Apr 2018
Posts: 13
Likes: 0
From: germany
When you pull the fuel pump hanger from the gas tank, at the top of the of the fuel pump there will be a hat shape object. Under it will be the top of the fuel pump, an o-ring and some other peice that is split in half. Replace the o-ring. The pipe that goes from the top of the fuel pump to the hanger is the stand pipe......... or so as I'm referring to it anyway.
you can get the o-ring from mazda or you can get the Dorman fuel injector o-ring variety pack from auto zone or something..... I've used both options.
you can get the o-ring from mazda or you can get the Dorman fuel injector o-ring variety pack from auto zone or something..... I've used both options.
Also, I am not running an OMP, Air Pump, AC, or Power steering. I was running the OMP before the rebuild, before all this difficulty starting issue.
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Joined: Apr 2018
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From: germany
Put in the new OEM FPR and some new spark plugs. Rx7 started, idled fine for awhile but I noticed at idle it was at +0.01 kpa and then occasionally would drop to vacuum and the idle would get shaky or it would rev way high. And then one time it dropped to like -145.0 kpa (vacuum I’m assuming) and the idle was at like 1600 forever and it pulse idled for a while before I tried adjusting the idle screw and it eventually died cause I think it was too low. Also my Pulsation dampener on the primary rail is leaking bubbles a tiny bit while the ignition is turned to on position. When I revved it it sounded super choppy and not smooth at all.
Last edited by Ludy Bahneman; Mar 19, 2019 at 02:59 PM.
Joined: Nov 2011
Posts: 3,425
Likes: 489
From: okinawa to tampa
youve got a lot more going on than it seems. any fuel leak is unacceptable regardless of how minor. if those are your idle numbers then theres 2 possibilities: theyre accurate and you and have a serious problem that i cant explain or you have a bad map sensor. replacing the oem fpr wont yeild any results. its a very simple part and it failing is infinitely unlikely. you already did so, its too late now. all the things you have deleted dont matter since you have a power fc but since you deleted the omp, you better be pre-mixing.
delete the pulsation damper, fix your leaks, replace the map sensor and try again.
delete the pulsation damper, fix your leaks, replace the map sensor and try again.
Thread Starter
Junior Member
Joined: Apr 2018
Posts: 13
Likes: 0
From: germany
youve got a lot more going on than it seems. any fuel leak is unacceptable regardless of how minor. if those are your idle numbers then theres 2 possibilities: theyre accurate and you and have a serious problem that i cant explain or you have a bad map sensor. replacing the oem fpr wont yeild any results. its a very simple part and it failing is infinitely unlikely. you already did so, its too late now. all the things you have deleted dont matter since you have a power fc but since you deleted the omp, you better be pre-mixing.
delete the pulsation damper, fix your leaks, replace the map sensor and try again.
delete the pulsation damper, fix your leaks, replace the map sensor and try again.
Last edited by Ludy Bahneman; Mar 19, 2019 at 03:18 PM.
Joined: Nov 2011
Posts: 3,425
Likes: 489
From: okinawa to tampa
There's a write up for deleting it that goes into detail. I mentioned earlier that higher than normal injector duty is a sign of low fuel pressure. Have you checked your fuel pressure yet?
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